Unveiling common responses of Medicago truncatula to appropriate and inappropriate rust species.

Little is known about the nature of effective defense mechanisms in legumes to pathogens of remotely related plant species. Some rust species are among pathogens with broad host range causing dramatic losses in various crop plants. To understand and compare the different host and nonhost resistance (NHR) responses of legume species against rusts, we characterized the reaction of the model legume Medicago truncatula to one appropriate (Uromyces striatus) and two inappropriate (U. viciae-fabae and U. lupinicolus) rusts. We found that similar pre and post-haustorial mechanisms of resistance appear to be operative in M. truncatula against appropriate and inappropriate rust fungus. The appropriate U. striatus germinated better on M. truncatula accessions then the inappropriate U. viciae-fabae and U. lupinicolus, but once germinated, germ tubes of the three rusts had a similar level of success in finding stomata and forming an appressoria over a stoma. However, responses to different inappropriate rust species also showed some specificity, suggesting a combination of non-specific and specific responses underlying this legume NHR to rust fungi. Further genetic and expression analysis studies will contribute to the development of the necessary molecular tools to use the present information on host and NHR mechanisms to breed for broad-spectrum resistance to rust in legume species.Financial support by Spanish AGL2011-22524 and Portuguese PEst-OE/EQB/LA0004/2011 grants is acknowledged. Maria Carlota Vaz Patto was supported by Fundação para a Ciência e a Tecnologia (Incentivos 2014 program).Peer Reviewe

Metabolomics profile responses to changing environments in a common bean (Phaseolus vulgaris L.) germplasm collection

Metabolomics is one of the most powerful -omics to assist plant breeding. Despite the recognized genetic diversity in Portuguese common bean germplasm, details on its metabolomics profiles are still missing. Aiming to promote their use and to understand the environment’s effect in bean metabolomics profiles, 107 Portuguese common bean accessions, cropped under contrasting environments, were analyzed using spectrophotometric, untargeted and targeted mass spectrometry approaches. Although genotype was the most relevant factor on bean metabolomics profile, a clear genotype × environment interaction was also detected. Multivariate analysis highlighted, on the heat-stress environment, the existence of higher levels of salicylic acid, and lower levels of triterpene saponins. Three clusters were defined within each environment. White accessions presented the lowest content and the colored ones the highest levels of prenol lipids and flavonoids. Sources of interesting metabolomics profiles are now identified for bean breeding, focusing either on local or on broad adaptation.To FCT, Portugal, in BEGEQA project (PTDC/AGR-TEC/3555/2012), E.M. PhD fellowship (SFRH/BD/89287/2012), as well as to R&D unit, UIDB/04551/2020 (GREEN-IT – Bioresources for sustainability) and COST Action FA1403 (STSM-FA1403-290815-063873) for funding. The authors also acknowledge PORTUGAL 2020 to the Portuguese Mass Spectrometry Network, grant number LISBOA-01-0145-FEDER-402-022125. The project NETDIAMOND (SAICTPAC/0047/2015), financially supported by FEEI (Lisboa 2020 and FCT/POCI-01-0145-FEDER-016385), to the iNOVA4Health (UID/Multi/04462/2013), financially supported by FCT and co-funded by FEDER under the PT2020 Partnership Agreement, as well as to POCI-01-0145-FEDER-029702, funded by FEDER funds through COMPETE2020 – Programa Operacional Competitividade e Internacionalização (POCI) and by national funds (PIDDAC) through FCT/MCTES

Resistance to rust and powdery mildew in Lathyrus crops

Several Lathyrus species, particularly Lathyrus sativus and L. cicera, have a high potential both as food and fodder crops. Rust and powdery mildew fungi are among the most important pathogens of major grain legumes including Lathyrus species. We review and critically discuss available knowledge of the existence of resistance and the underlying resistance mechanisms against rust and powdery mildew in the L. sativus and L. cicera crop species.We would like to acknowledge financial support from Integrated Portuguese-Spanish Action, Conselho de Reitores das Universidades Portuguesas, Portugal/Ministe - rio de Ciencia y Tecnología, Spain (E-95/04, AGL2011-22524). M.C. Vaz Patto was supported by Fundação para a Ciência e a Tecnologia, Lisboa, Portugal (Research Contracts by the Ciên - cia 2008 program and PTDC/AGR-GPL/103285/2008 project).Peer Reviewe

Medicago truncatula host/nonhost legume rust interactions

Book Editor(s): Frans de Bruijn.Medicago truncatula is a model species to study legume defense mechanisms against rust infection. Different studies have characterized its host interactions with Uromyces striatus (alfalfa rust), and its nonhost resistance to other related rust species. The present review assesses how these studies allowed to understand the mechanisms of resistance operative in host and nonhost rust interactions, opening ways for the development of the necessary tools to speed up breeding for durable broad‐spectrum resistance to rust in otherwise unexplored legume crops.Peer reviewe

Lathyrus diversity: Available resources with relevance to crop improvement - L. sativus and L. cicera as case studies

[Background] The Lathyrus genus includes 160 species, some of which have economic importance as food, fodder and ornamental crops (mainly L. sativus, L. cicera and L. odoratus, respectively) and are cultivated in >1·5 Mha worldwide. However, in spite of their well-recognized robustness and potential as a source of calories and protein for populations in drought-prone and marginal areas, cultivation is in decline and there is a high risk of genetic erosion. [Scope] In this review, current and past taxonomic treatments of the Lathyrus genus are assessed and its current status is examined together with future prospects for germplasm conservation, characterization and utilization. A particular emphasis is placed on the importance of diversity analysis for breeding of L. sativus and L. cicera. [Conclusions] Efforts for improvement of L. sativus and L. cicera should concentrate on the development of publicly available joint core collections, and on high-resolution genotyping. This will be critical for permitting decentralized phenotyping. Such a co-ordinated international effort should result in more efficient and faster breeding approaches, which are particularly needed for these neglected, underutilized Lathyrus species. © 2014 The Author.The authors would like to acknowledge the financial support of Fundação para a Ciência e a Tecnologia, Portugal, through grants #PEst-OE/EQB/LA0004/2011 and #PTDC/AGR-GPL/103285/2008 and Research Contract by the Ciência 2008 program (to M.C.V.P.). This research was also funded by FP7-ARIMNet-MEDILEG project and by Spanish project AGL2011-22524.Peer Reviewe

Lathyrus research in Portugal

Lathyrus spp. in Portugal are nowadays underutilized crops. The main species grown are L. sativus (grass pea) for food and L. cicera (chickling vetch) for feed.Peer reviewe

Fusarium Wilt Management in Legume Crops

© 2020 by the authors.Legumes are among the most important crops worldwide for human and animal consumption. However, yield inconsistency due to susceptibility to pests and diseases strongly affects its production. Among diseases affecting legumes, Fusarium wilt caused by the soil-borne pathogen Fusarium oxysporum Schltdl. (Fo) is one of the major factors limiting production worldwide. This disease can cause total losses in highly infested fields of some legume species. To minimize yield losses, integrated disease management strategies combining different agronomic practices with the use of resistant varieties should be applied. Although often characterized by a high degree of host specificity, with formae speciales (ff. spp.) and races identified, some Fo ff. spp. can have a broader host range, infecting more than one species, requiring further investigation. In this review, we describe the state of the art on legume Fusarium wilt management achievements, highlighting different aspects such as the use of rhizosphere microbiota as biocontrol agents, crop rotation and the use of resistant varieties. The different methods of identification and characterization of resistance sources, mechanisms as well as the genetic basis of resistance or the development of molecular tools to support legume precision breeding for Fo resistance are discussed.This research was funded by Fundação para a Ciência e Tecnologia (FCT), Portugal through grant PD/BD/114118/2016 (A.M.S.), the PhD holder contract (DL57) (S.d.S.A.), the IF/01337/2014 FCT Investigator contract (M.C.V.P.), the research unit GREEN-IT (UID/04551/2020), the QuaLaty project (PTDC/AGR-TEC/0992/2014) and the Spanish Research Agency (AEI) project AGL2017-82907-R.Peer reviewe

Association Mapping of Lathyrus sativus Disease Response to Uromyces pisi Reveals Novel Loci Underlying Partial Resistance

Uromyces pisi ([Pers.] D.C.) Wint. is an important foliar biotrophic pathogen infecting grass pea (Lathyrus sativus L.), compromising their yield stability. To date, few efforts have been made to assess the natural variation in grass pea resistance and to identify the resistance loci operating against this pathogen, limiting its efficient breeding exploitation. To overcome this knowledge gap, the genetic architecture of grass pea resistance to U. pisi was investigated using a worldwide collection of 182 accessions through a genome-wide association approach. The response of the grass pea collection to rust infection under controlled conditions and at the seedling stage did not reveal any hypersensitive response but a continuous variation for disease severity, with the identification of promising sources of partial resistance. A panel of 5,651 high-quality single-nucleotide polymorphism (SNP) markers previously generated was used to test for SNP-trait associations, based on a mixed linear model accounting for population structure. We detected seven SNP markers significantly associated with U. pisi disease severity, suggesting that partial resistance is oligogenic. Six of the associated SNP markers were located in chromosomes 4 and 6, while the remaining SNP markers had no known chromosomal position. Through comparative mapping with the pea reference genome, a total of 19 candidate genes were proposed, encoding for leucine-rich repeat, NB-ARC domain, and TGA transcription factor family, among others. Results presented in this study provided information on the availability of partial resistance in grass pea germplasm and advanced our understanding of the molecular mechanisms of quantitative resistance to rust in grass pea. Moreover, the detected associated SNP markers constitute promising genomic targets for the development of molecular tools to assist disease resistance precision breeding.This work was supported by the Fundação Para a Ciência e Tecnologia through the grant PD/BD/128498/2017 (DM), the R&D Research Unit GREEN-IT—Bioresources for Sustainability (UIDB/04551/2020 and UIDP/04551/2020), and the Agencia Española de Investigación grant PID2020-11468RB-100 (DR).Peer reviewe

RNA-seq of plant/pathogen interactions as a tool for deciphering effector genes

Trabajo presentado en la 2nd Annual Conference of the SUSTAIN Action, celebrada en Zakopane (Poland) del 15 al 17 de octubre de 2014.Rusts are among the most important plant diseases. As biotrophic fungi, there is a requirement to sustain infected host cells alive for their development, increasing the need for an efficient cross-talk between host and pathogen. Rusts are also known for the frequent breakdown of resistance due to the rapid evolution of these pathogens. RNA-seq can provide valuable information about plant/pathogen interactions, allowing the identification and quantification of expressed sequences potentially involved in plant resistance and in the pathogen attack. Using this approach on resistant and susceptible Lathyrus accessions, we identified the potential effectors involved in the Uromyces pisi/Lathyrus sativus and U. pisi/L. cicera interactions. From the 4558 putative fungal transcripts, 891 encoded potential secreted proteins, as predicted by SignalP and TargetP algorithms.From these, a selection of effector proteins will be used as probes to identify the target host proteins as an initial step towards the development of effector-driven legume breeding approaches, maximizing the potential of durability of resistance against such a quickly evolving pathogen.N

Grass pea and pea phylogenetic relatedness reflected at Fusarium oxysporum host range

Vascular wilt, caused by the infection of the soil-borne pathogen Fusarium oxysporum (Fo), is one of the most destructive diseases of many crops, including legumes such as grass pea (Lathyrus sativus), with several formae speciales (ff. spp.) defined according to their hosts. Commonly described as host-specific, Fo could, in some cases, show a broader host range comprising related plant species, making its host range characterization an important aspect of epidemiology and crop protection. No information on identification and host range status of strains able to infect grass pea is available, nor whether grass pea could act as host to different Fo ff. spp.. In this study, the host range of two Fo strains isolated from grass pea (Fo ex. L. sativus 1 and 2) was evaluated using related legume species: pea (Pisum sativum), lentil (Lens culinaris), chickpea (Cicer arietinum), common bean (Phaseolus vulgaris), and barrel medic (Medicago truncatula). In addition, the responses of grass pea to the causal agents of fusarium wilt in these legume species, Fo f. sp. pisi, lentis, ciceris, phaseoli, and medicaginis, were also investigated. Disease symptom evaluation by disease rating over time, its related area under disease progress curve (AUDPC) and disease progress rate (DIr), revealed that Fo ex. L. sativus 1 and 2 are host-specific, infecting only grass pea although with low aggressiveness. Grass pea could also be infected by Fo f. sp. pisi races, with race 2 being the most virulent strain in grass pea, even more virulent than the Fo strains retrieved originally from grass pea. The phylogenetic relatedness between grass pea and pea may in part explain this observation, indicating that Fo f. sp. pisi can also infect legume-related species such as grass pea. Additionally, specialization might be occurring, with particular Fo isolates being only virulent to grass pea, although with lower virulence than Fo f. sp. pisi race 2 itself. These cross-inoculation results reinforce the importance of performing host-range studies, even on specialist pathogens, to identify potential closely related alternative hosts and consequently improve or adapt disease control management.Financial support by Fundação para a Ciência e Tecnologia (FCT), Portugal, is acknowledge through grant PD/BD/114418/2016 (A.M.S.), the IF/01337/2014 FCT Investigator contract (M.C.V.P.), the research unit GREEN-IT (UID/04551/2020), the QuaLaty project (PTDC/AGR-TEC/0992/2014) and the Spanish Research Agency (AEI) project AGL2017-82907-R